The Blue, Green Ocean From Above. Chlorophyll-a From Satellite Ocean Colour

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Ocean Science in Action - Oceans of the future

4. Introduction to remote sensing

4.2 The Blue, Green Ocean From Above. Chlorophyll-a From Satellite Ocean Colour

Video duration - 05:41

Satellite-borne ocean colour sensors can detect variations in the colour of the ocean due to the presence of chlorophyll in phytoplankton (small algae), which changes the water colour from blue to green.

Since the launch of the SeaWiFS satellite in 1997, a series of ocean colour sensors have provided continuous measurements of chlorophyll concentration over the global ocean. Due to the effects of fronts, eddies and regions of upwelling on phytoplankton growth, these ocean colour data also reveal much about physical processes occurring within the ocean.

Growth, mortality, the availability of nutrients, and grazing by zooplankton all affect the abundance of phytoplankton present in the water. Processes that raise or lower the depth of the biota will affect the amount of phytoplankton in the surface layer that the satellite ”sees”. The sensor can only detect phytoplankton near the surface, and in the absence of clouds, which otherwise would obscure its view of the sea surface.

Dr F. Jebri, Prof M. Srokosz - NOC

Further Reading:

IOCCG (2000). Remote Sensing of Ocean Colour in Coastal, and Other Optically-Complex, Waters. Report 3, Edited by Shubha Sathyendranath, pp. 140 (

Groom S et al. (2019). Satellite Ocean Colour: Current Status and Future Perspective, Front. Mar. Sci.

Sathyendranath, S., Brewin, R.J., Brockmann, C., Brotas, V., Calton, B., Chuprin, A., Cipollini, P., Couto, A.B., Dingle, J., Doerffer, R. and Donlon, C., 2019. An Ocean-Colour Time Series for Use in Climate Studies: The Experience of the Ocean-Colour Climate Change Initiative (OC-CCI). Sensors, 19(19), p.4285.

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